In a semiconductor device fabrication process, for example, as the surface of a semiconductor wafer should always be kept clean, a cleaning process is performed on the semiconductor wafer adequately. As a typical example of a single wafer type cleaning process of processing semiconductor wafers one by one, a process method is known which performs a cleaning process by feeding a predetermined chemical liquid to a semiconductor wafer held by a spin chuck or causing a rotary brush to abut on the surface of a semiconductor wafer, then performs a rinse process of feeding pure water to the semiconductor wafer, and then further rotates the semiconductor wafer at a high speed to spin the pure water off the semiconductor wafer.
However, such a process method has a problem such that micro water residue remains on the surface of the semiconductor wafer, which appears as water marks. When the surface of the semiconductor wafer which is not completely dried is in contact with air, that portion is oxidized, generating water marks.
As a method which suppresses generation of such water marks, Unexamined Japanese Patent Application Publication No. 2001-53051 discloses a substrate dry method which sprays an inactive gas to the center portion of a substrate after a rinse process, sprays pure water to the outer peripheral portion of the substrate, and moves the spray position of the inactive gas and the spray position of the pure water outward from the substrate in the radial direction.
The method disclosed in the publication does not however achieve sufficient reduction of water marks at the circumferential portion of a substrate to be processed. As an inactive gas is fed after pure water is moved off the center of the substrate, water marks are likely to be generated in the center portion of the substrate. In this respect, there is demands for a substrate cleaning method and a substrate cleaning apparatus which can further suppress generation of water marks.